U.S. patent application number 14/992427 was filed with the patent office on 2017-07-13 for electric component.
The applicant listed for this patent is E I DU PONT DE NEMOURS AND COMPANY. Invention is credited to Akira INABA.
Application Number | 20170200556 14/992427 |
Document ID | / |
Family ID | 58010367 |
Filed Date | 2017-07-13 |
United States Patent
Application |
20170200556 |
Kind Code |
A1 |
INABA; Akira |
July 13, 2017 |
ELECTRIC COMPONENT
Abstract
The present invention relates to an electric component
comprising a main body, a terminal electrode on at least one side
of the main body and a hot-melt polymer layer on the terminal
electrode, wherein the hot-melt polymer layer comprises a metal
powder, a polymer and a wax.
Inventors: |
INABA; Akira; (Kawasaki-Shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E I DU PONT DE NEMOURS AND COMPANY |
Wilmington |
DE |
US |
|
|
Family ID: |
58010367 |
Appl. No.: |
14/992427 |
Filed: |
January 11, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23K 35/0244 20130101;
B23K 35/025 20130101; B23K 35/3013 20130101; H01G 4/30 20130101;
H01G 2/065 20130101; B23K 35/404 20130101; H01G 4/0085 20130101;
B23K 35/302 20130101; B23K 35/3033 20130101; B23K 35/262 20130101;
B23K 35/3006 20130101; H01G 4/248 20130101; B23K 35/3613 20130101;
B23K 35/282 20130101; B23K 35/286 20130101 |
International
Class: |
H01G 4/008 20060101
H01G004/008; H01G 4/248 20060101 H01G004/248; H01G 4/30 20060101
H01G004/30 |
Claims
1. An electric component comprising a main body, a terminal
electrode on at least one side of the main body and a hot-melt
polymer layer on the terminal electrode, wherein the hot-melt
polymer layer comprises a metal powder, a polymer and a wax.
2. The electric component of claim 1, wherein the hot-melt polymer
layer is 1 to 30 .mu.m thick.
3. The electric component of claim 1, wherein the metal powder is
selected from the group consisting of silver, copper, gold,
palladium, platinum, rhodium, nickel, aluminum, gallium, indium,
tin, zinc, bismuth and a mixture thereof.
4. The electric component of claim 1, wherein glass transition
point (Tg) of the polymer is -25 to 180.degree. C.
5. The electric component of claim 1, wherein the polymer is
selected from the group consisting of ethyl cellulose, polyvinyl
butyral resin, phenoxy resin, hydroxypropyl cellulose resin,
polyester resin, phenolic resin, epoxy resin, acrylic resin,
melamine resin, polyimide resin, polyamide resin, polystyrene
resin, butyral resin, polyvinyl alcohol, polyurethane resin,
silicone resin and a mixture thereof.
6. The electric component of claim 1, wherein the wax is selected
from the group consisting of vegetable wax, animal wax, mineral
wax, petroleum wax, synthetic wax and a mixture thereof.
7. The electric component of claim 1, wherein the wax is selected
from the group consisting of bayberry wax, candelilla wax, carnauba
wax, castor oil, esparto wax, jojoba oil wax, ouricury wax, rice
bran wax, soy wax, tallow tree wax, beeswax, wool wax, shellac wax,
spermaceti, ceresin wax, montan wax, montan-ester wax, paraffin
wax, microcrystalline wax, ozocerite wax, peat wax, paraffin wax,
microcrystalline wax, petroleum jelly wax, fischer-tropsch wax,
polyethylene wax, polyolefin wax, polypropylene wax, amide wax,
fatty acid wax, fatty acid ester wax and a mixture thereof.
8. The electric component of claim 1, wherein the metal powder is
100 parts by weight, the polymer is 0.5 to 20 parts by weight, and
the wax is 0.1 to 50 parts by weights.
9. The electric component of claim 1, wherein the electric
component is be selected from the group consisting of a resistor, a
capacitor, an inductor and a semiconductor chip.
10. A method of manufacturing an electric component comprising
steps of: providing a main body of the electric component
comprising a terminal electrode formed on at least one side of the
main body; applying a hot-melt polymer paste on the terminal
electrode, wherein the hot-melt polymer paste comprises a metal
powder, a polymer, a wax and a solvent; and drying the applied
hot-melt polymer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an electric component and a
method of manufacturing thereof.
TECHNICAL BACKGROUND OF THE INVENTION
[0002] An electric component is mounted on a circuit by using a
solder. The solder needs to smoothly spread out on a terminal
electrode of the electric component. The solder layer having voids
could negatively affect electrical properties of the electric
component.
[0003] EP0720187 discloses a multiple-layered capacitor having a
terminal electrode that is made of a composition containing a
silver particle, a glass frit having a glass transition point of
400-500.degree. C. and a glass softening point of 400-550.degree.
C., and an organic vehicle.
BRIEF SUMMARY OF THE INVENTION
[0004] An objective is to provide an electric component to be
soldered with few voids.
[0005] An aspect of the invention relates to an electric component
comprising a main body, a terminal electrode on at least one side
of the main body and a hot-melt polymer layer on the terminal
electrode, wherein the hot-melt polymer layer comprises a metal
powder, a polymer and a wax.
[0006] Another aspect of the invention relates to a method of
manufacturing an electric component comprising steps of: providing
a main body of the electric component comprising a terminal
electrode formed on at least one side of the main body; applying a
hot-melt polymer paste on the terminal electrode, wherein the
hot-melt polymer paste comprises a metal powder, a polymer, a wax
and a solvent; and drying the applied hot-melt polymer.
[0007] An electric component being soldered with few voids can be
provided by the present invention.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a schematic cross-sectional drawing of the
electric component.
[0009] FIG. 2 is a schematic cross-sectional drawing of the
electrical device before soldering.
[0010] FIG. 3 is a schematic cross-sectional drawing of the
electric component after soldering.
[0011] FIG. 4 is a side view of a test piece of the electric
component used in the Example.
DETAILED DESCRIPTION OF INVENTION
[0012] An electric component and a method of soldering the electric
component are explained below.
Electric Component
[0013] An electric component 100 as a capacitor is shown in FIG. 1.
The capacitor 100 comprises a main body 101, terminal electrodes
104 on both sides of the main body, and hot-melt polymer layers 105
on the terminal electrodes in an embodiment. The terminal electrode
104 is defined as an electrode electrically and physically joined
with an external conductive element such as a circuit. The main
body 101 of the capacitor is a laminate comprising insulating
ceramic layers 102 and internal electrodes 103 in an
embodiment.
[0014] The terminal electrode 104 can be a fired-type electrode or
a cured-type electrode in an embodiment. The fired-type electrode
can be formed by applying a conductive paste comprising typically a
conductive powder, a glass frit and an organic vehicle; and firing
the conductive paste in an embodiment. The firing temperature is
400 to 1000.degree. C. in an embodiment.
[0015] The cured-type electrode can be formed by applying a
heat-curable conductive paste comprising typically a conductive
powder and a thermosetting polymer; and curing the heat-curable
conductive paste in an embodiment. The curing temperature is 120 to
390.degree. C. in an embodiment. The conductive powder can be
selected from the group consisting of silver, gold, platinum,
copper, nickel and a mixture thereof in another embodiment. The
terminal electrode 104 is 5 to 100 .mu.m thick in an
embodiment.
[0016] The hot-melt polymer layer 105 is formed on the terminal
electrodes 104. The hot-melt polymer layer 105 melts at a reflow
temperature. Reflow is a heating process to solder the electric
component and the circuit. The hot-melt polymer layer 105 is 1 to
30 .mu.m thick in an embodiment, 3 to 25 .mu.m thick in another
embodiment and 5 to 15 .mu.m thick in another embodiment.
[0017] The hot-melt polymer layer 105 comprises a metal powder, a
polymer and a wax. The hot-melt polymer layer 105 comprises no
glass frit in an embodiment. The hot-melt polymer layer 105
comprises no cross-linking agent in another embodiment.
[0018] The method of manufacturing the electric component comprises
steps of, providing an electric component comprising a main body
and a terminal electrode on at least one side of the main body,
applying a hot-melt polymer paste on the terminal electrode, and
drying the applied hot-melt polymer paste. The hot-melt polymer
layers 105 can be applied on the terminal electrode 104 by for
example dipping, screen printing and transfer printing in an
embodiment. The applied hot-melt polymer paste is then dried out to
remove the solvent. The drying temperature can be 50 to 200.degree.
C. in an embodiment, 60 to 180.degree. C. in another embodiment, 90
to 160.degree. C. in another embodiment.
[0019] The hot-melt polymer layer 105 can be partially formed on
the terminal electrode 104 in another embodiment. The hot-melt
polymer layer 105 can be formed on the terminal electrode at least
at the area of contingence with a solder paste as being mounted
thereon. At least 70% of the surface of the terminal electrode 104
can be covered with the hot-melt polymer layer 105 in another
embodiment. The hot-melt polymer layer 105 can be formed on the
entire surface of the terminal electrode 104 in another
embodiment.
[0020] In another embodiment, the terminal electrode can be only
one side of the main body. The electric component can comprise a
main body, a terminal electrode on just one side of the main body
and a hot-melt polymer layer on the terminal electrode in another
embodiment. The terminal electrode can be formed on a bottom
surface of the main body 101 in another embodiment. The bottom
surface of the main body is the side facing the circuit in another
embodiment.
[0021] The electric component 100 is mounted on an electric circuit
board as shown in FIG. 2 in an embodiment. The electric circuit
board comprises a substrate 201 and a circuit 202 on the surface of
the substrate in an embodiment. The substrate 201 can be rigid or
flexible in an embodiment. The substrate 201 can be a paper phenol
substrate, a paper epoxy substrate, a glass epoxy substrate, a
ceramic substrate, a low temperature co-fired ceramic (LTCC)
substrate, a polymer film, a glass substrate, a ceramic substrate
or a combination thereof in another embodiment. The circuit 202 can
be made with a plated metal, a metal foil or a thick film
conductive paste in an embodiment.
[0022] A solder paste 203 is applied on the circuit 202 in an
embodiment. The solder paste 203 comprises a solder powder and a
flux in an embodiment. The solder powder is a metal alloy
containing a metal having low melting point. The solder paste 203
comprises a solder powder selected from the group consisting of
Sn/Pb, Sn/Pb/Bi, Sn/Sb, Sn/Cu, Sn/Ag/Cu, Sn/Zn/Bi, Sn/Zn/Al,
Sn/Ag/In/Bi and Sn/Ag/Cu/Ni and a mixture thereof in an
embodiment.
[0023] The solder paste 203 is lead-free in another embodiment. A
lead-free solder is environment-friendly, however often causes less
solderability compared to a lead-containing solder. The electric
component of the present invention could have sufficient
solderability even in use of a lead-free solder paste.
[0024] The solder paste is purchasable in the market, for example,
Eco Solder.RTM. from Senju Metal Industry Co., Ltd., Evasol.RTM.
from Ishikawa Metal Co., Ltd. and Fine Solder.RTM. from Matsuo
Handa Co., Ltd.
[0025] The electric component 100 is mounted on the solder paste
203 as the hot-melt polymer layers 105 come thereon as shown in
FIG. 2 in an embodiment.
[0026] The assembly is then heated, so-called "reflow" where the
solder melts by the heat to electrically and physically connect the
electric components 100 and the circuit 202. Heating may be
accomplished by passing the assembly through a reflow oven or under
an infrared lamp or by soldering individual joints with a hot air
pencil.
[0027] The reflow temperature is 100 to 350.degree. C. in an
embodiment, 150 to 310.degree. C. in another embodiment, 200 to
290.degree. C. in another embodiment. The reflow time is 1 to 60
second(s) in an embodiment, 4 to 30 seconds in another embodiment,
and 6 to 20 seconds in another embodiment. The heating temperature
and time are adjustable in consideration of their combination such
as low temperature for long time and high temperature for short
time.
[0028] The solder paste 203 melts to spread out upward on the
terminal electrodes 104 as fusing the hot-melt polymer layer during
the reflow as shown in FIG. 3. The metal powder in the hot-melt
polymer layer 105 could melt into an alloy with the molten solder
203. The polymer in the hot-melt polymer layer could move away as
the molten solder spread out on the terminal electrode due to its
higher specific gravity. The specific gravity of the solder is 7 to
10 g/cm.sup.3 in an embodiment. The specific gravity of the polymer
is 0.8 to 2.0 in an embodiment.
[0029] The electric component 100 can be selected from the group
consisting of a resistor, a capacitor, an inductor and a
semiconductor chip in an embodiment.
[0030] The hot-melt polymer paste to form the hot-melt polymer
layer is explained hereafter. The hot-melt polymer paste comprises
a metal powder, a polymer, a wax and a solvent.
Metal Powder
[0031] The metal powder can be selected from the group consisting
of silver, copper, gold, palladium, platinum, rhodium, nickel,
aluminum, gallium, indium, tin, zinc, bismuth and a mixture thereof
in an embodiment. The metal powder can be selected from the group
consisting of silver, nickel, tin, zinc, bismuth and a mixture
thereof in another embodiment. The metal powder can be silver in
another embodiment.
[0032] The metal powder can be flaky, spherical, nodular or a
mixture thereof in shape in an embodiment. The metal powder can be
flaky in shape in another embodiment. The metal powder can be
spherical in shape in another embodiment.
[0033] The particle diameter (D50) of the metal powder can be 0.5
to 20 .mu.m in an embodiment, 0.7 to 15 .mu.m in another
embodiment, 0.9 to 10 .mu.m in another embodiment, 1 to 5 .mu.m in
another embodiment, 0.5 to 2 .mu.m in another embodiment, 3 to 5
.mu.m in another embodiment. The metal powder with such particle
size can disperse well in the organic vehicle. The particle
diameter (D50) is obtained by measuring the distribution of the
powder diameters by using a laser diffraction scattering method
with Microtrac model X-100.
Polymer
[0034] The hot-melt polymer layer comprises a polymer. The metal
powder disperses in the polymer. The polymer is soluble at
25.degree. C. in an organic solvent used in the hot-melt polymer
paste.
[0035] Glass transition point (Tg) of the polymer is -25 to
180.degree. C. in an embodiment, 10 to 168.degree. C. in another
embodiment, 120 to 180.degree. C. in another embodiment, 10 to
50.degree. C. in another embodiment. The polymer starts alternating
rigid crystalline and elastic amorphous regions at its glass
transition point.
[0036] Molecular weight (Mw) of the polymer is 500 to 300,000 in an
embodiment, 10,000 to 260,000 in another embodiment, 13,000 to
230,000 in another embodiment, 50,000 to 200,000 in another
embodiment, and 100,000 to 190,000 in another embodiment.
[0037] The polymer can be selected from the group consisting of
ethyl cellulose, polyvinyl butyral resin, phenoxy resin,
hydroxypropyl cellulose resin, polyester resin, phenolic resin,
epoxy resin, acrylic resin, melamine resin, polyimide resin,
polyamide resin, polystyrene resin, butyral resin, polyvinyl
alcohol, polyurethane resin, silicone resin and a mixture thereof
in an embodiment. The polymer can be selected from the group
consisting of ethyl cellulose, polyvinyl butyral resin, phenoxy
resin, polyester resin, epoxy resin and a mixture thereof in
another embodiment. The polymer comprises ethyl cellulose in
another embodiment. The hot-melt polymer paste comprises no
thermosetting polymer in another embodiment.
[0038] The polymer is thermoplastic in an embodiment.
[0039] The polymer is 0.5 to 20 parts by weight in another
embodiment, 1 to 15 parts by weight in another embodiment, 1.5 to
10 parts by weight in another embodiment, 2 to 7 parts by weight in
another embodiment against 100 parts by weight of the metal
powder.
Wax
[0040] Wax is a type of lipid that is malleable at 20.degree. C.
and turn to liquid at between 30 and 300.degree. C. Melting point
of the wax is 30 and 300.degree. C. in another embodiment. The wax
is selected from the group consisting of vegetable wax, animal wax,
mineral wax, petroleum wax, synthetic wax and a mixture thereof in
another embodiment.
[0041] The vegetable wax is selected from the group consisting of
bayberry wax, candelilla wax, carnauba wax, castor oil, esparto
wax, jojoba oil, ouricury wax, rice bran wax, soy wax, tallow tree
wax and a mixture therefor.
[0042] The animal wax is selected from the group consisting of
beeswax, wool wax, shellac wax, spermaceti and a mixture thereof in
another embodiment.
[0043] The mineral wax is selected from the group consisting of
ceresin wax, montan wax, montan-ester wax, paraffin wax,
microcrystalline wax, ozocerite wax, peat wax and a mixture thereof
in another embodiment.
[0044] The petroleum wax is selected from the group consisting of
paraffin wax, microcrystalline wax, petroleum jelly and a mixture
thereof in another embodiment.
[0045] The synthetic wax is selected from the group consisting of
fischer-tropsch wax, polyethylene wax, polyolefin wax,
polypropylene wax, amide wax, hydrogenated oil, fatty acid wax,
fatty acid ester wax and a mixture thereof. The fatty acid wax is
stearic acid in an embodiment.
[0046] The wax is selected from the group consisting of bayberry
wax, candelilla wax, carnauba wax, castor oil, esparto wax, jojoba
oil wax, ouricury wax, rice bran wax, soy wax, tallow tree wax,
beeswax, wool wax, shellac wax, spermaceti, ceresin wax, montan
wax, montan-ester wax, paraffin wax, microcrystalline wax,
ozocerite wax, peat wax, paraffin wax, microcrystalline wax,
petroleum jelly wax, fischer-tropsch wax, polyethylene wax,
polyolefin wax, polypropylene wax, amide wax, fatty acid wax, fatty
acid ester wax and a mixture thereof in another embodiment.
[0047] The wax is selected from the group consisting of castor oil,
montan wax, montan-ester wax, polyethylene wax, polypropylene wax,
amide wax, fatty acid wax and a mixture thereof in another
embodiment.
[0048] The wax is 0.1 to 50 parts by weight in an embodiment, 1 to
38 parts by weight in another embodiment, 2 to 15 parts by weight
in another embodiment.
Solvent
[0049] The solvent can be used to dissolves the polymer. The
solvent evaporates during drying out the hot-melt polymer paste on
the terminal electrode.
[0050] The solvent is 2 to 60 parts by weight in an embodiment, 9
to 50 parts by weight in another embodiment, 15 to 40 parts by
weight in another embodiment against 100 parts by weight of the
metal powder.
[0051] Boiling point of the solvent can be 120 to 350.degree. C. in
an embodiment, 160 to 320.degree. C. in another embodiment, 200 to
290.degree. C. in another embodiment.
[0052] The solvent can be an organic solvent in an embodiment.
[0053] The solvent can be selected from the group consisting of
texanol, 1-phenoxy-2-propanol, terpineol, carbitol acetate,
ethylene glycol, butyl carbitol, dibutyl carbitol, dibuthyl acetate
propylene glycol phenyl ether, ethylene glycol monobutyl ether and
a mixture thereof in another embodiment.
[0054] The solvent can be used to adjust the viscosity of the
hot-melt polymer paste to be preferable for applying on the
substrate. Viscosity of the polymer paste is 10 to 300 Pas measured
by Brookfield HBT with a spindle #14 at 10 rpm in an embodiment. In
the event of dipping, the viscosity of the conductive paste can be
10 to 120 Pas.
Additive
[0055] An additive such as a surfactant, a dispersing agent, a
stabilizer and a plasticizer can be added to the polymer paste
based on a desired property of the paste.
Example
[0056] The present invention is illustrated by, but is not limited
to, the following examples.
[0057] The hot-melt polymer paste was prepared as follows.
[0058] A spherical silver powder was dispersed in a mixture of an
ethyl cellulose (Mw: about 180,000, Tg: 130.degree. C.,
Ethocel.RTM. STD-100, Dow Chemical Company), a solvent, and a
polypropylene wax (CERAFLOUR.RTM. 970, BYK-Chemie Japan) by mixing
well in a mixer followed by a three-roll mill until the metal
powder was dispersed well. The polypropylene wax was a synthetic
wax. The solvent was a mixture of texanol and 1-Phenoxy-2-propanol.
The paste viscosity was adjusted by adding the solvent to about 30
Pas measured by Brookfield HBT with a spindle #14 at 50 rpm.
Particle diameter (D50) of the silver powder was 1.3 .mu.m. The
amount of each material is shown in Table 1.
[0059] The hot-melt polymer layer prepared above was screen printed
on the cured-type electrode 402 formed on a ceramic substrate 401
as shown in FIG. 4. The cured-type electrode 402 was prepared in
advance, formed by screen printing a heat-curable conductive paste
on the ceramic substrate 401 followed by heating at 170.degree. C.
for 30 minutes. The cured-type electrode consisted of 91 wt. % of a
copper powder and 9 wt. % of a phenolic resin. The cured-type
electrode 402 was a square of 12 mm wide, 25 mm long, 22 .mu.m
thick. The printed hot-melt polymer paste 403 was heated at
120.degree. C. for 30 minutes, thereby the solvent in the paste
evaporated. The hot-melt polymer layer 403 was a square of 12 mm
wide, 25 mm long and 15 .mu.m thick.
[0060] A Pb-free solder paste 404 (Sn/Ag/Cu=96.5/3/0.5, M705, Senju
Metal Industry Co., Ltd.) was screen printed on the hot-melt
polymer layer 403. The pattern of the solder paste 404 was a circle
of 6 mm diameter and 200 .mu.m thick.
[0061] The ceramic substrate with the layers of the electrode, the
hot-melt paste and the solder paste was placed on a hot-plate to
reflow at 240.degree. C. for 30 seconds. During the reflow, the
solder paste melted to spread out on the electrode.
[0062] After cooling down to room temperature, number of void
appeared in solder layer at a unit area of 1 mm.sup.2 was visually
counted.
[0063] The void decreased when the hot-melt paste contained the wax
as Example (Ex.) 1 to 6 showed in comparison of Comparative Example
(Com. Ex.) 1. Sufficient solderability with spreading out was
observed in all Examples and Comparative Example.
TABLE-US-00001 TABLE 1 (Parts by weight) Com. Ex. 1 Ex. 1 Ex. 2 Ex.
3 Ex. 4 Ex. 5 Ex. 6 Ag Powder 100 100 100 100 100 100 100 Ethyl 5 5
5 5 5 5 2.5 cellulose resin Solvent 75 75 75 75 75 75 52.5
Polypropylene 0 3 6 10 15 30 10 wax Voids 8.8 0.7 0.3 0.3 2.8 3.3
0.9
[0064] Next, the variety of wax was examined. The ceramic substrate
with the layers of the electrode, the hot-melt paste and the solder
paste was formed in the same manner as Example 1 above except for
using different kind of wax as shown in Table 2. The amide wax, the
polyethylene wax, the polypropylene wax, and the fatty acid wax are
synthetic waxes. The castor oil is a vegetable wax. The montan wax
and the montan-ester wax are mineral waxes.
[0065] The void on the solder layer was counted as well as Example
1. With any kind of wax, the void appeared less as shown in Example
7 to 13.
TABLE-US-00002 TABLE 2 (Parts by weight) Ex. 7 Ex. 8 Ex. 9 Ex. 10
Ex. 11 Ex. 12 Ex. 13 Ag Powder 100 100 100 100 100 100 100 Ethyl 5
5 5 5 5 5 5 cellulose resin Solvent 75 75 75 75 75 75 75 Amide
wax.sup.1) 10 0 0 0 0 0 5 Castor oil.sup.2) 0 10 0 0 0 0 0 Montan 0
0 10 0 0 0 0 wax.sup.3) Montan-ester 0 0 0 10 0 0 0 wax.sup.4)
Polyethylene 0 0 0 0 10 0 0 wax.sup.5) Fatty acid 0 0 0 0 0 10 0
wax.sup.6) Polypropyl- 0 0 0 0 0 0 5 ene wax.sup.7) Voids 0 2.1 0.2
0.6 0.3 0.9 0.2 .sup.1)CERAFLOUR .RTM. 994, BYK-Chemie Japan K.K.
.sup.2)DISPARLON .RTM. 308, Kusumoto Kasei Co. Ltd. .sup.3)Licowax
.RTM. LP, Clariant Ltd. .sup.4)Licowax .RTM. E, Clariant Ltd.
.sup.5)Licowax .RTM. R21, Clariant Ltd. .sup.6)Stearic acid, Wako
Pure Chemical Industries Ltd. .sup.7)CERAFLOUR .RTM. 970,
BYK-Chemie Japan K.K.
[0066] Next, variety of the polymer was examined. The ceramic
substrate with the layers of the electrode, the hot-melt paste and
the solder paste was formed in the same manner as Example 1 above
except for using different kinds of polymers as shown in Table 3.
The void was counted as well as Example 1. With all kinds of
polymer, the void appeared less than six as shown in Example 14 to
16.
TABLE-US-00003 TABLE 3 (Parts by weight) Ex. 14 Ex. 15 Ex. 16 Ag
Powder 100 100 100 Solvent 65 40 54 Polypropylene wax 10 10 10
Polyvinyl butyral resin.sup.8) 5 0 0 Phenoxy resin.sup.9) 0 5 0
Polyester resin.sup.10) 0 0 16 Voids 5.1 5.2 2.8 .sup.8)S-LEC B
.RTM. BH-S, SEKISUI CHEMICAL Co., LTD., Mw: 66,000, Tg: 64.degree.
C. .sup.9)PKHH, InChem Corporation, Mw: 52,000, Tg: 92.degree. C.
.sup.10)Nichigo-POLYESTER .RTM. TP249, Nippon Synthetic Chemical
Industry Co., Ltd., Mw: 16,000, Tg: 36.degree. C.
* * * * *